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tcp: annotate sk->sk_rcvbuf lockless reads

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For the sake of tcp_poll(), there are few places where we fetch
sk->sk_rcvbuf while this field can change from IRQ or other cpu.

We need to add READ_ONCE() annotations, and also make sure write
sides use corresponding WRITE_ONCE() to avoid store-tearing.

Note that other transports probably need similar fixes.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2019-10-10 20:17:44 -07:00
committed by David S. Miller
parent d9b55bf7b6
commit ebb3b78db7
7 changed files with 15 additions and 12 deletions
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4
net/ipv4/tcp.c
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@@ -451,7 +451,7 @@ void tcp_init_sock(struct sock *sk)
icsk->icsk_sync_mss = tcp_sync_mss;
sk->sk_sndbuf = sock_net(sk)->ipv4.sysctl_tcp_wmem[1];
sk->sk_rcvbuf = sock_net(sk)->ipv4.sysctl_tcp_rmem[1];
WRITE_ONCE(sk->sk_rcvbuf, sock_net(sk)->ipv4.sysctl_tcp_rmem[1]);
sk_sockets_allocated_inc(sk);
sk->sk_route_forced_caps = NETIF_F_GSO;
@@ -1711,7 +1711,7 @@ int tcp_set_rcvlowat(struct sock *sk, int val)
val <<= 1;
if (val > sk->sk_rcvbuf) {
sk->sk_rcvbuf = val;
WRITE_ONCE(sk->sk_rcvbuf, val);
tcp_sk(sk)->window_clamp = tcp_win_from_space(sk, val);
}
return 0;